Device for changing the gears automatically on a synchronized gearbox

ABSTRACT

A processing device capable of starting the sequence of the speed change operations automatically in the gearbox of a vehicle, such as the automatic transmission of a truck. A first comparator compares the data received from a gearbox condition detecting device and that received from a speed ratio selection device. In the event of a difference, the comparator sends to a gearbox control device either a pulse for increasing by one speed ratio, or a pulse for decreasing by one speed ratio.

This is a division of application Ser. No. 563,377, filed on Mar. 31, 1975, and now U.S. Pat. No. 4,140,031.

The present invention relates to a processing device intended for the automatic control of the course of the changing of gears in a synchromesh gearbox. The device can also be used on a gearbox with individual synchromesh devices, as well as a gearbox with a collective synchromesh device.

The invention relates more particularly to gearboxes of motor vehicles, and especially to gearboxes of trucks, lorries and heavy trucks and lorries.

BACKGROUND OF THE INVENTION

The control of gearboxes of known types used on trucks and lorries is carried out by the driver, according to a complex process, the automatic character of which is obtained by training the driver (declutching, passing to neutral, gearing, coupling, and on occasion, double declutching operation or double action on the accelerator pedal).

The processing device according to the present invention ensures the course of the gear-changing operations automatically, while taking into account all possible cases, as a very good truck or lorry driver would do, without ever committing any mistake.

SUMMARY OF THE INVENTION

The present invention provides a processing device for automatically controlling changes of speed in a synchronized gearbox associated with a clutch on a vehicle. The processing device is used in combination with a gearbox having change members, and a gearbox control device which is operatively connected with and controls the change members of the gearbox. The processing device also includes a device (200) for selection of speed ratios, a device (500) for detecting the condition of the gearbox, and a first comparator (302). The processing device also includes an electronic assembly having logic elements. The electronic assembly has an input section which includes the first comparator (302) operably and electrically connected between the speed ratio selection device (200) and the gearbox condition detecting device (500). The electronic assembly has its output operably and electrically connected to the gearbox control device (400) for controlling the change members of the gearbox.

The main features of the novel processing device are as follows:

(1) The operation of the device is sequential, with a check of the execution of a step required for the start of the next step. This enables safe operations of optimum rapidity.

(2) The device is checked by itself through systems which detect the mistaken codes, and it adjusts itself by itself to a change in the condition of the vehicle, either during the ratio changing operation, or after a parasitic perturbance.

(3) From the very start of the ratio change cycle, the device supplies data about the nature of said change (progression or retrogression). This is necessary for the ratio selection device in every case, and, in particular, in the case where a collective synchromesh device is used. In this way, the monitoring of the suitable synchronizing members can be started from the very start of the change of ratio, which allows saving time in a substantial way with respect to the total duration of the speed ratio change.

(4) The device ensures the monitoring of the clutch during the ratio changes.

(5) The device detects the impossibilities of engagement of a ratio owing to the position "tooth against tooth" of the male and female parts of a dog. It causes the clutch to be closed by pulse so as to allow the gearing to take place (this can take place when the vehicle is at a standstill, with the engine throttled down, that is, with the clutch released).

(6) The device can be blocked during its cycle by an outer order given, for instance, by a synchronism detector, in order that the step "engaging the new ratio" starts in the cycle only after the authorization by the synchronism detector is emitted.

Various other features and objects of the present invention will become apparent from the following description and appended claims, reference being had to the accompanying non-limiting drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the general structure of a preferred embodiment of the processing device according to the present invention which may be used in conjunction with the gearbox of a truck.

FIGS. 2 through 5 depict the shapes of certain signals at various locations in the circuitry depicted in FIG. 1.

DETAILED DESCRIPTION

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, because the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

The processing device illustrated by FIG. 1 includes essentially logic elements, such as AND gates, OR gates, delay units, and the like. The arrangement constitutes an electronic assembly connected to the cover of a gearbox, and, namely, to a gearbox control device 400 which drives the gearbox (gear control forks or jacks).

The structure of such processing device will be understood from the following description of its operation:

A ratio code, selected by a device 200 for selection of the ratio, is presented to the input of a temporary storage memory 301, which transmits the ratio code to a first input of a first comparator 302 (a binary comparator, for instance, a four-bit comparator).

A code of the gearbox condition (i.e., whether the gearbox is in neutral, or else which gear ratio is engaged), worked out or elaborated by a device 500, is presented to the second input of the comparator 302.

The comparator 302 detects:

either a sameness, in which case no modification of the condition of the gearbox is necessary,

or a difference, in which case a change of ratio is necessary, with the following alternative:

if the code of the ratio selected is higher than the code of the gearbox condition, a "progression" will be selected (the ratios will be "raised");

if the code of the ratio selected is lower than the code of the gearbox condition, a "regression" will be selected (one ratio will be retrograded).

The first comparator 302 emits the change of ratio data, and a further data characterizing the nature of said change. From the very start of the cycle, the data "Progression" or "Regression" will be stored by a temporary storage means 326, and is available for the external uses specified.

The development of a change of ratio of the gearbox is as follows.

When the first comparator 302 finds that the two signals received are not identical any longer, it stops emitting a (1) on the input of delay unit 303, which is a delay circuit intended to avoid taking fleeting mistaken detections into account. NOT gate 304 allows obtaining a (1) when the sameness ceases. AND gate 305 emits an order to execute the change of ratio if the unbalance of the comparator 302 and the validity of the codes are confirmed by the devices 306, 329, 330, 331 and 332. The "validity of the codes" relates to the confirmation that no fault has been detected in the codes. For example, if the code initially chosen for handling information provides for an even number of bits for any correct code, and an uneven code appears, then such fault (or lack of parity) is immediately detected. In order that a cut wire or a disconnected connection prohibits any dangerous operation, the validity detector 306 detects the "0 0 0 0" code, which is never used, and would correspond to a disconnected connection, while parity checking device 330, AND gate 331, NOT gate 332 and parity checking device 329 are devices checking the evenness or parity of the binary code used.

The executive order emitted by the AND gate 305 brings about the following events:

order to store, for the temporary storage means or memory 326 of the nature of the change of ratio;

order to "open" the clutch;

order to bring the bearbox into "Neutral," through OR gate 312, third AND gate 319, "Neutral" coding device 320, AND gate 321, OR gate 322, and control device 400. This order is inhibited via a "Neutral" decoding device 316 if the gearbox is already in "Neutral";

order to store, for the memory 301 of the ratio selected if the following conditions are complied with:

(a) checking the parity of the code of the ratio selected by parity checking device 310, this parity should be correct;

(b) the order to execute must be present;

(c) the NOT gate 307 and second AND gate 313 imply or impose the obligation not to have the "Neutral" and the output code of the memory 301 smaller than the input code of the memory 301 simultaneously. Such a situation is possible only if the memory 301 is already in a storing condition. The input code of the memory 301 is still the code selected, but the output code of the memory 301 is then called the "imposed code" for the duration of the ratio change cycle.

During a change of ratio, the speed of the vehicle may increase or decrease. If the ratio selected becomes greater than the ratio imposed, there is a risk of overspeed for the engine. Such an occurrence is prevented by a second comparator 311 which, through delay unit 312 and AND gate 313, inhibits the order to store sent by an AND gate 309 to the memory 301. The contents of the memory 301 are brought up-to-date as to the new ratio selected. At the same time, an order to pass to "Neutral" is sent by the devices 327, 314, 319, 321, 322 and 400, while, through NOR gate 328 and AND gate 315, a "Neutral" memory 317 of passage to Neutral is deleted. The object of this arrangement is to impose passing to "Neutral" in all cases.

In the event of the ratio imposed being modified by the action of second comparator 311, etc., it is known that it is necessarily a progression, so that the temporary storage means, or memory 326 of the nature of the change of condition, must be suitably positioned by an order to force. In this connection, because the new imposed ratio will necessarily be "higher" than the original ratio if memory 301 is brought up-to-date as set forth hereinabove, the change for passing into a "suitable position" will necessarily be a progression. Therefore, the contents of memory 326 are forced, i.e., imposed without any other consideration. The order "to force" is an order to impose the position of a bistable, among the two possible positions.

Lastly, as regards the ratio changes which consist in progressions, it is desirable to hold the "imposed ratio" for some time after the clutch is "closed," in order that the speed of the vehicle again reaches a correct value. This is obtained by means of a second delay unit or system 308, which allows the executive order given to AND gate 309 to disappear only after a time τ₂ if the operation is a progression. A delay system 325 is provided in order that, after a perid of time τ₃ greater than a normal change of ratio, after the beginning of the execution of the order, there is an emissin of a closing pulse for the clutch during a period of time τ₄ sufficient for unlocking the dogs which are in tooth-to-tooth contact, without causing shaking of the vehicle.

The above events precede the engagement of the new ratio.

Engagement of the Imposed Ratio

The code of the imposed ratio, delivered by the memory 301 via devices 324, 322 and 400, is engaged, if the following requirements are combined together at the inputs of AND gate 323;

external condition=1

"Neutral" memory=1

executive order=1

After the ratio imposed is engage, the system or device 500 presents to the first comparator 302 a code of condition identical with the imposed code, and the executive signal disappears, as well as:

the order to open the clutch

the orders to store for the following memories:

memory 301 of ratio (with delay in the event of a progression)

memory 326 of nature of the change

memory 317 of "Neutral."

The system is now ready to receive a new selected ratio.

Description of the Passage to "Neutral"

The passage to "Neutral" is obtained in the following manner, if the gearbox has a ratio engaged:

Decoding device 316 for "Neutral" indicates (0) on the "Neutral" memory 317.

The advent of an executive order brings about:

(a) the order to store in memory 317 through AND gate 315, if AND gate 327 via NOT gate 328 does not find any fault;

(b) the order to pass to neutral through devices 314, 319, 320, 321, 322 and 400 because the "Neutral" decoding device 316 emits a (0) transmitted by "Neutral" memory 317 and inverted by NOT gate 318, which makes it possible to pass through AND gate 319.

As soon as the passage to neutral is obtained, the device 500 will emit its "neutral" code, which will be acknowledged by decoding device 316, the latter then emitting (1) towards memory 317 which stores this data and transmits it to NOT gate 318, the latter inverting it and locking AND gate 319. For the same reason, AND gate 321 becomes locked and control device 400 no longer receives (via OR gate 322) the "Neutral" code generated by 320.

On the other hand, the (1) at the output of memory 317 unlocks AND gate 323 which permits conveying of the code imposed towards control device 400 via OR gate 322.

The "Neutral" memory 317 allows keeping AND gate 323 unlocked during the passage from "neutral" to the ratio imposed. This memory will be deleted at the end of the cycle.

When the device is brought up-to-date on a new ratio in the course of operation, the "Neutral" memory 317 will be deleted by the devices 311, 312, 327 and 328, while the "Neutral" will be controlled by the devices 311, 312, 327, 314, 319, 320, 321, 322 and 400.

The position "Neutral" must be considered as the position which must necessarily be reached in any manipulation in order to avoid serious mishaps, even when the gearbox is equipped with mechanical safety means.

FIGS. 2 to 5 illustrate the shapes of the signals at various locations of the circuit, namely:

the signal E at the input of the delay system τ₂ (FIG. 2);

the signal S at the output of the delay system τ₂ (FIG. 3);

the signal E₁ at the input of the delay system τ₃ (FIG. 4);

the signal S₃ at the output of the delay system τ₄ (FIG. 5).

There is herein incorporated by reference the following disclosures: commonly-assigned copending U.S. patent application, Ser. No. 479,537 filed on June 14, 1974, naming Jean-Paul Sibeud as inventor, and entitled "DEVICE WITH A JACK FOR CONTROLLING A GEARBOX SYNCHROMESH, AND METHOD FOR USING SAME"; commonly-assigned U.S. Pat. No. 3,943,792 issued Mar. 16, 1976, naming Jean-Paul Sibeud as inventor, and entitled "METHOD AND DEVICE FOR ASCERTAINING THE STATE OF A GEARBOX, IN PARTICULAR IN A MOTOR VEHICLE"; commonly-assigned copending U.S. patent application, Ser. No. 469,232 filed on May 13, 1974, naming Jean-Paul Sibeud as inventor, and entitled "AUTOMATIC CLUTCH DEVICE FOR MOTOR VEHICLES", now abandoned; and commonly-assigned copending U.S. patent application, Ser. No. 561,247 filed Mar. 24, 1975 naming Jean-Paul Sibeud as inventor, and entitled "DEVICE FOR THE AUTOMATIC OR MANUAL SELECTION OF THE RATIO OF A GEARBOX ON A MOTOR VEHICLE" and claiming Convention priority from French patent application No. 7411844 filed Mar. 26, 1974 (French Publication No. 2,265,568). The disclosures of all of the aforementioned applications are hereby incorporated herein by reference thereto. 

We claim:
 1. A processing device for automatically controlling changes of speed in a synchronized gearbox associated with a clutch of a vehicle, comprising, in combination:a gearbox having change members; a gearbox control device (400) operatively connected with and controlling said change members of said gearbox; a device (200) for selection of speed ratios; a device (500) for detecting the condition of said gearbox; a first comparator (302); an electronic assembly including logic elements; said electronic assembly having an input section which includes said first comparator (302) operably and electrically connected between said speed ratio selection device (200) and said gearbox condition detecting device (500); said electronic assembly having its output operably and electrically connected to said gearbox control device (400) for controlling said change members of said gearbox; said input section of said electronic assembly also including a memory device (301) for the temporary storage of the code of a selected ratio; said memory device (301) being operably and electrically connected between said speed ratio selection device (200) and said first comparator (302); said speed ratio selection device (200) selecting a ratio code and transmitting said selected ratio code to the input of said temporary storage memory (301); said gearbox condition detection device (500) producing a gearbox condition code and transmitting said bearbox condition code to said first comparator (302); and, when said first comparator (302) detects a difference between said ratio code and said gearbox condition code, said first comparator (302) emitting:a "progression" pulse for increasing by one speed if the selected ratio code is greater than said gearbox condition code; and a "regression" pulse for decreasing by one speed if the selected ratio code is less than said gearbox condition code; said electronic assembly also including a validity detector (306) operably and electrically connected to said temporary storage memory (301); said temporary storage memory (301) transmitting an input code to said validity detector (306); said detector (306) detecting the validity of the input code received from the temporary storage memory (301); said electronic assembly also including a first AND gate (305), a "Neutral" memory (317), and a temporary storage means (326); the output of said validity detector (306) and the output of said first comparator (302) being both connected as inputs to said first AND gate (305); the output of said first AND gate (305) being electrically connected to and shared between said "Neutral" memory (317), said temporary storage means (326), and said gearbox control device (400); said first AND gate (305) emitting an executive order to execute the change of ratio when the imbalance of the first comparator (302) and the validity of the codes are confirmed; said executive order producing:an order for said temporary storage means (326) to memorize the nature of said change of ratio; an order to open the clutch; an order to bring the gearbox into "Neutral"; and an order to store said selected ratio code in said temporary storage memory (301) when the following three requirements are met: (a) the parity of the selected ratio code has been checked and found correct; (b) said executive order is present; and (c) said temporary storage memory (301) is not already in a storage condition.
 2. A processing device according to claim 1, wherein:said electronic assembly also includes a "Neutral" decoding device (316) operably and electrically connected between said gearbox condition detecting device (500) and said "Neutral" memory (317); and said "Neutral" decoding device (316) inhibits said order to bring the gearbox into "Neutral" if the gearbox is already in "Neutral."
 3. A processing device according to claim 2, wherein:said temporary storage memory (301) supplies at its output an "imposed code" if said order to store said selected code ratio occurs when said temporary storage memory (301) is already in a storing condition; and said "imposed code" remains imposed during the entire duration of the cycle of the speed ratio change.
 4. A processing device according to claim 3, wherein:said electronic assembly also includes a second comparator (311), a first delay unit (312), and a second AND gate (313); said second comparator (311) being connected electrically in parallel with said temporary storage memory (301); said second comparator (311) having its output transmitted to said first delay unit (312); said first delay unit (312) having its output transmitted to the input of said second AND gate (313); said "Neutral" decoding device (316) having its output transmitted to the input of said second AND gate (313); and said second comparator (311) inhibits the order to store sent to said temporary storage memory (301) when the selected ratio becomes greater than the imposed ratio which occurs if the engagement of the selected ratio would risk making the input shaft of the gearbox, and consequently the engine which drive the gearbox, to run with overspeed.
 5. A processing device according to claim 4, wherein:said electronic assembly also includes a second delay unit (308) which holds the imposed ratio for some time after the clutch is closed in order to allow the vehicle to pick up speed again when said "progression" pulse is emitted.
 6. A processing device according to claim 5, wherein:said electronic assembly also includes a delay system (325) which is electrically connected in parallel across said temporary storage means (326) during the change of ratio; said delay system (325) having a delay duration which is longer than that of a normal change of ratio; said delay system (325) emits a clutch closing pulse during a period of time sufficient for unlocking dogs of said clutch should said dogs be in tooth-to-tooth engagement at the time the vehicle starts; and the delay of said delay system (325) and said emitting of said clutch closing pulse taking place before the engagement of a new ratio.
 7. A processing device according to claim 4, wherein:said electronic assembly also includes a first NOT gate (318) and a third AND gate (319); said third AND gate (319) having one input being fed from the output of said first NOT gate (318) and another input being fed from the output pulse of said first comparator (302); and if the gearbox has a ratio engaged, the passage to Neutral takes place according to the following process: (a) order to store the executive order if no fault has been found; and (b) order to pass to Neutral because the "Neutral" decoding device (316) emits a zero which is transmitted by said "Neutral" memory (317) and then inverted by said first NOT gate (318) which in turn unlocks said third AND gate (319) and actuates the change members of the gearbox. 